Weighing machine



Dec. 13; 1927.

A. BOUSFIELD WEIGHING MACHINE -Filed Nov. 1 s; 1925 Fig.1.

15 F1H.E. 21 13 16 L 12 1 Fig.5. I

INVENTOR Alfred Bog f'lkrld,

ATTORNEY Patented Dec. 13, 1927.

UNITED STATES PATENT OFFICE.

ALFRED BOUSF IELD, OF ST. JOHNSBURY, VER-MONT,ASSIGNOR T0 E. AND T.FAIR- BANKS AND COMPANY, OF ST. J OHNSBURY, VERMONT, A CORPORATION OFZ,VER-

IVIONT.

WEIGHING MACHINE.

Application filed November 13, 1925.

My present invention relates to weighing machines, and has for itsobject to provide an improved knife edge pivot therefor.

In order that a scale may weigh properly, the pivots in scale levers andbeams must be placed with great exactness and the practice of castingthe levers with the pivots in place results in the loss of many castingsowing to the pivots having been improperly placed or having shifted inthe mould. Furthermore, the pivots lose their temper and often warpduring the casting process and must be re-shaped and re-hardened, whichinvolves grinding and heating operations that, when the pivots are fixedin the lever, are diflicult to carry out, especially if the lever be aheavy one. lVhere a pivot is thus fixed in place it must be formed of abar of sufficient cross-section to support the weight, and as these barsare of high-grade steel, their cost is considerable. The practice ofinserting the pivots in holes drilled in the lever is also followed tosome extent, but such inserted pivots must be formed of even heavierbars than are used to form pivots which are fixed in place in castingand the cost of such inserted pivots is therefore also very great. Insome types of scales it has been the custom to form the pivots with acylindrical portion that is mounted in holes drilled in the lever orother scale part, and projecting longitudinally from such cylindricalportion are the knife edges. The cylindrical portion of the pivots ofthis character have greater area than the knife edge portion, however,in. manufacturing this type of pivot, considerable difiiculty has beenexperienced in machining the parts whereby the knife edges will beproperly alined.

Generally stated, a pivot falling within the scope of my invention iscomposed of two pieces, one of which is cylindrical in form and providedwith a rectangular groove, the bottom of which groove lies along thelongitudinal axis of the cylinder, and the other piece is substantiallyrectangu lar in form for engaging with the sides of the groove, and hasa knife edge portion resting on the bottom of the groove, the secondpiece being frictionally retained by the first piece, and the firstpiece being frictionally line 33 of Fig. 2;

Serial No. 68,760.

mounted in a hole drilled in the lever or other scale part, both piecesbeing fixed in position without using auxiliary fastenings.

The invention is illustrated in the accompanyingdrawings in which Figure1 is an elevation of a weighing machine, showing the application of myinvention thereto;

Fig. 2, is a horizontal section taken approximately on the line 22 ofFig. 1, most of the parts being shown in plan;

Fig. 3, is a transverse section taken on the 4 is a detail view of thepivot, and

Fig. 5 is a transverse section taken on the line 5-5 of Fig. 4.

My invention can be used in the various plvotal connections of weighingor other like machines, therefore, I have chosen to show in the presentembodiment the same applied to the scale shown in United States LettersPatent #1,346,481 issued July 13, 1920.

Referring now to the drawings, the arm 12 is pivotally mounted by meansof a pivot 13 seated on bearings 14 carried in the top of a support 15.The forward segmental end 16 of the arm has attached thereto a tape 17,while an eccentric 18 to which is attached a tape 19 is. mounted so asto extend rearwardly of the pivot 13. Both of the tapes are connected toother parts of the scale mechanism and function in the manner fullydescribed in the patent, the arm swinging on its pivot during theoperation of the scale in the usual well known manner.

For the purpose of facilitating construc tion of scale parts it has beenthe custom to form the arm from a casting. One end of the arm isbifurcated to provide a pair of spaced hubs 20 in which are drilledalined openings 21 for receiving the pivot. The eccentric 18 is carriedby the pivot in the space between the hubs 20 (see Figs. 2 and 3.)

As shown, the pivot comprises a cylindrical body from which projectsalined knife edges that are disposed coincident with the longitudinalaxis of the main body of the pivot. Heretofore pivots of this characterhave been formed in various ways. Some have been cut from a solid pieceof material, while others have been composed of assembled parts suitablyfastened together. In all cases, however, accurate machining of theparts is required so as to obtain articles suitable for use in sensitiveweighing machines.

In order to produce a pivot wherein the oppositely projecting knifeedges would be in perfect alinement, considerable machining and grindinghas been required, which work has unreasonably increased the costof thearticles. Furthermore, it has also been dill.- cult for the workmen todetermine with accuracy whether or not the two knife edges were properlyalined. Therefore, in order to obtain a better article which could bereadily manufactured at little expense, the pivot 13 is composed of twopieces, a cylindrical body, which is madefroin a suitable length ofround barsteel, and knife edge portion 22, which is made from a suitablelength of rectanguiar'bar steel. i

In producing the pivot, the cylindrical body portion has a rectangularchannel or groove23 formed the length thereof, such groove havingparallel sides and a flat bottom 24, which latter is disposed coincidentwith the longitudinal'axis of the body. The

knife edge bar 22, which has a wedge-shaped portion '25 tapering fromparallel sides 26, is adapted to be driven or pressed into the groove 23with the lower edge ofthe portion 25 seated along the bottom 24. Informing the pivot, it is the practice to. form the groove 23 of a widthcorresponding tothe thickness of the knife edge bar 22. The

sharpened edge portion of the bar is carefully ground before thepartsare assembled. Should the upper edge of the bar project above thesurface of the cylindrical body, after the bar has been properly seatedin the groove, the exterior surface of the pivotcan be ground down tothe desired diameter that will enable the pivot to be driven into properposition in the openings 21 of the arm 12. 'ihisconstruction has enabledan accurate article to be produced without resorting to the use ofscrews, bolts or other auxiliary fastenings for securing the partstogether.

Having thus described my invention, what I claim is Y 1. A scale pivotcomprising a cylindrical body portion having a substantially rectanguiargroove extending longitudinally thereof and a knife-edged bar havingparallei side faces'for frictionaiiyengaging the side walls of saidgroove, said knife edge resting on the bottom wall of said groove andbeing spaced from the side wall thereof 2. A scale'pivot comprising acylindrical body portion having a substantially rectangular grooveextending longitudinally thereof and a knife-edged bar having parallelside faces for frictionaily engaging the side walls of said groove, saidknife edge resting on the bottom wall of said groove.

In testimony whereof I hereunto sign my name. I t V ALFRED BOUSFIELD.

